Use the power of the sun for a solar composter DIY project for winter composting solutions to keep your compost composting!
Chickens are a fantastic way to repurpose food scraps, but if eggs aren’t in your diet or you’ve got scraps chickens don’t care for (I’m talking about you, citrus rinds and pepper seeds), composting is a wonderful way to go “table-to-farm,” as we say in my house.
A pile on the ground is a simple system. If you can’t put a pile just outside your kitchen or you have limited space, buying a tumbler-style composter may be tempting. These make the turning a cinch, but because the compost isn’t in contact with the ground, it doesn’t benefit from the Earth’s heat. The compost itself will generate heat, but when the weather is too cold for the bacteria to work and your compost pile is only tumbler-sized, you’ll get frozen zucchini peels instead of rich, brown ambrosia.
So, what to do? Simple. Build an eco-friendly house around the composter with big south-facing upcycled windows, thick insulation, and plenty of easy access to the great outdoors. This will gather the sun’s heat and keep winter at bay longer during colder seasons. It’s also a fun way to build something without committing to a massive project.
Around the homestead, I’ve never regretted putting equipment on wheels. Big swivel casters, coupled with lawn-mower wheels, will put your compost house closer when it’s time to dump compost out but will allow you to keep it out of the way when company comes over for a barbecue. Most importantly, wheels will let you change your south-facing window into a north-facing window when the season heats up, so you don’t kill the microbiome in summer. Depending on where you store the bin, and whether you’re up to the task of a two-tone paint job, dark, absorbent paint on one side can face the sun in winter, and a light, reflective wall can face the sun in summer.
In general, this build is pretty straightforward, but spend some time thinking about a few details. First, the bin will get heavy, so a robust and well-supported base should be a priority. Second, because you’ll need access to top-load and side-unload, ensure there’s enough bracing to accommodate all those hinges and doors.
A quick word of caution: Shelter of any kind is attractive to critters, but a warm winter shelter can be especially tempting. Make seals relatively tight, especially on the bottom. Making this composter roomy enough to see critters will turn it into a bulky build, so prioritize good seals.
If you don’t have sufficient material to assemble this, convince a buddy to make a garden shed or a tiny house, and you’ll have everything you need from the leftover scraps. If that’s not an option, some home centers sell bits and remnants at a discount, and a local Habitat for Humanity store might be a goldmine. You’ll want deck screws – the powder-coated cousins of drywall screws – as they’ll resist rusting for a lot longer. An oil-change drip tray or a water-heater pan can also provide secondary containment for when things inevitably get sloppy with compost tea concentrate and the leftover asparagus casserole that sat in the fridge too long.
The roof will be spared from the worst of the mess, but you might not like holding it up with your head while you dump compost inside. A pair of gas pistons will prop it up like a hatchback, which will be much nicer than using a stick that falls out when you bump it. The corrugated composite lid shown is held up by two 9-inch pistons rated at 22 pounds each. It may take trial and error to get them where you want them, but they’re worth it. You’ll need larger pistons for composite roofs than for metal roofs, which may hold up better to the constant opening and closing than their asphalt counterparts (beware of the sharp edges!). On the flip side, heavier might be better if you’re in an area prone to wind.
The gas-pistoned lid will make it convenient to fill the bin, but at some point, all of that goodness will have to come out and fulfill its destiny. This house will need a front door, plenty tall and wide to get the composter in and out. Once you add insulation inside, it can get cozy, making it difficult to turn the drum over and handle it going in and out. Allow yourself at least 3 inches on all sides to keep it from rubbing and to give your hand a place to go when you want to grab it.
Insulation will better allow this tiny house of goodness to moderate the temperature. If you insulate the floor, have a durable surface between the insulation and the composter, so the insulation doesn’t turn into ground-up chips. The tighter the insulation, the better it’ll be, so consider adding canned spray-in foam to the cracks; just be aware that it’s messy to apply and messy if it rubs against anything both before and after it’s cured. If those filled-in cracks are big enough for critters, think about wadding up some hardware cloth, chicken wire, or aluminum window screen and put it in there before the spray foam; it’ll make it hard to chew through. You can attach purpose-made aluminum-clad foam insulation with several construction adhesives – the aluminum can withstand most things. If you choose upcycled polystyrene packaging and want to glue it rather than bolt it down with big fender washers, do a test run first to ensure your glue doesn’t eat foam for lunch. Foam tape can seal up the doors, although stapled-on strips of a recycled fleece jacket can adequately hold seams. There certainly is a satisfaction that comes with repurposing materials on a project like this, even if it isn’t photogenic.
It took me a long time to learn that you can’t just throw kitchen scraps in a bin and expect soil to come out. For the type and quantity of degradable waste my family generates, we must add a healthy supply of dry grass clippings or leaves to keep it from turning into swamp mush. We’ve found that if these additives aren’t stored near the bin, they don’t end up there. As you plan this project out, consider your dry-matter needs. Ours is a 5-gallon bucket posted nearby, but it might be classier to build a bonus room on this tiny compost house and let the dry grass clippings live out their days as neighbors in a compost bin duplex.
Josh Lau is an engineer, professional inventor, and Eagle Scout. He raises chickens and steers on a small ranch in Central Oregon with his patient wife and awesome kids.
